One of the most well-known styles of running is to swing your arms and hands forwards and backwards to match the forwards and backwards motion of the opposite leg and foot (hereafter, the “swinging arms technique”). By way of example, FIG. 26 illustrates one cycle of a swinging arms technique. Frames (c) through (e) show the runner's center of mass continuing forward as the runner's left foot remains planted on the ground. As the left foot moves behind the runner, the runner's right hand moves behind the runner as well. Indeed, when the runner's left foot is in maximum contact with the ground as shown in frame (d), the vast majority of the momentum in the runner's right hand is moving backwards and parallel to the ground. When performing the swinging arms technique, the runner's hands also tend to move in opposite vertical directions while one of the runner's feet is on the ground. For example, as the runner moves from the position shown in frame (c) to the position shown in frame (d), the runner's left hand moves down (and backwards) and the runner's right hand moves up (and forwards). As a result, when using the swinging arms technique, one hand is typically moving primarily backwards and the other hand is moving primarily upwards at the moment a foot is in maximum contact with the ground.
It has been proposed that running with hand-held, wrist or leg weights while using the swinging arm technique will help a person intensify the effort of running for the purposes of burning more calories and increasing one's endurance. However, at least some experts in the field of sprinting believe that training to run faster by carrying weights while using the swinging arm technique is counter-productive because carrying the weights interferes with the coordination and timing to maintain the necessary stride frequencies to sprint fastest when the weights are not carried. Regardless of whether training with weights results in positive or negative results, people tend to run slower when they hold weights in their hand or wear them on their wrist while performing the swinging arms technique.
It has been advertised that certain products can help a runner perform better if they use the product while running. For instance, at least some have asserted that a person can run faster and more efficiently if they wear certain types of athletic footwear than no footwear at all. By way of example, spiked track and field shoes typically have rigid foot beds and spikes to create better traction and rebound off the ground.